Various blow molding devices have been developed in an effort to increase the efficiency and production rate of fabricating blow molded articles. A common method of increasing the efficiency and production rate of a blow molding apparatus is to provide multiple blow molding stations for use in connection with a single parison extruder. Using such a method, parisons can be inserted into one mold cavity while blow molded articles are cooling in other mold cavities, thereby reducing the idle time of the extruder during production.
Different types of multiple blow molding station devices operate based on different primary principles. One method of operating a multiple blow molding station device is to provide multiple molding stations that revolve about an axis. Such devices are configured to perform different operations at various points along the rotational path traversed by the molding stations. An example of such a device is disclosed in U.S. Pat. No. 4,801,260, which is herein incorporated by reference in its entirety. These types of devices are advantageous in that they allow a single extruder to be used to extrude parisons into multiple molds and allow molded products to be discharged from each of the molds at a common stationary discharge or take-out station. However, there are also disadvantages associated with rotary multi-molding station devices. One such disadvantage is that the molding stations must revolve in order to proceed from one operational station to the next and therefore production must be completely stopped when performing routine service on any one of the molding stations.
Other types of multiple blow molding station devices utilize multiple molding stations that linearly reciprocate relative to an extruder. An example of such a reciprocating multiple molding station blow molding apparatus is disclosed in U.S. Pat. No. 6,499,988, which is hereby incorporated by reference in its entirety. While these reciprocating devices have advantages, they too have disadvantages. One such disadvantage of linear reciprocating devices is that they require relatively more bulky and higher maintenance drive mechanisms to move the molding stations than do the rotary type blow molding devices. Such drive mechanisms typically comprise hydraulic or pneumatic fluid actuators of sufficient length so as to be extendable by an amount equal to the distance that mold stations travel when reciprocating. Another disadvantage is that fluid supply lines for providing air, hydraulic fluid, water, or other fluids to the movable molding stations from non-movable portions of such devices must be flexible to accommodate the linear reciprocation. Invariably, such flexible fluid conduits fatigue, and thereby require maintenance throughout the useful operational life of the molding device.
In view of the foregoing, it should be appreciated that numerous developments have been made regarding multiple blow molding station devices. However, it should also be appreciated that improvements over existing multiple blow molding station devices can be made.